John beooks



(No Model.)

J. BROOKS.

BED POR ZINCOGRAPEIG PRESSES.

110.v 312,325. Patented Peb. 17, 1885.

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BED FOR ZNCOGRAPHIC PRES-SES.

SLQECFI Tl\l forming part of Letters Patent No. 312,325, dated February17, 1885.

Application filed March Il, 189.4. (No model.)

To @ZZ 'whom t may concern:

Be it known that I, JOHN BROOKS, of Plainfield, in the county of Unionand State OfNew Jersey, have invented a new and useful Improvement inBeds for Zincographic Presses, and the following is declared to be adescription of the same.

Plates of zinc are sometimes employed for printing instead of thelithographie stone, on account of cheapness and occupying less spacewhen packed away. It has heretofore been very difficult tosatisfactorily stretch the Zinc sheets so as to bring them down flat andeven upon the bed-plate of the press.

My invention relates to mechanism for grasping and securing the oppositeedges of the zinc plate, and for stretching the same and imparting to itany desired amount of tension.

My invention consists of a metal bed, upon which the zinc plate is laid.One edge of said bed is beveled, and upon it a bar is secured by screws.One edge of the sheet of zinc is placed between the beveled edge and thebar, and is securely held by a projection or rib on the bar and agroovein the beveled ed ge, which groove is preferably V -shaped. Theother edge of the sheet of zinc is bent over a wire or rod, and is laidin a groove upon the inclined surface of a bar or series of bars, and itis held in place by a clamping bar or series of bars, either screwedupon the aforesaid bars or connected to them by links. The bar or seriesof bars having the inclined surfaces are connected to and supported byrods sliding in openings in the frame of the bed, and these rods areymoved endwise to stretch the zinc plate by screw-rods, also passingthrough open ings in the frame of the bed, and having a bearing againsta plate screwed upon the side of the bed.

In the drawings, Figure l is a cross-section and partial elevation of myimproved bed.

d is secured to the beveled edge c by screws, and upon its under surfacethere is a rib or projection, preferably V-shaped, and fitting thegroove in said edge. rlhe sheet of zinc is laid between the beveled edgeand the bar and pressed into this groove by the projection on the bar,so as to securely hold the sheet in i screws g, the points of which passinto the slots.

The screws h have heads h and collars 11, and said screws pass throughopenings in the frame or ribs of the bed, the collars 'L' being inrecesses in the bed-frame, as shown in Fig. l.

.A bar or plate, 7;, having slots for the screw h, is secured to thebed-frame, and confines the collars t', and forms a stop to prevent theendwise movement of the screw-rods h, and serves as a bearing for thecollars. The screws pass into the sliding or guide rods g, and therevolution of said screws imparts a forward or backward movement to theguide-rods g and the bars e. The shcet'of zinc is bent around awire orrod, b, and is laid in shallow grooves in both the surfaces of the barse and clamping-bars f, and said bars f are secured upon the inclinedface of e by screws. After this side of the sheet of zinc is secured inthis manner it is stretched by revolving the screw-rods l1. and forcingout the guide-rods g and bars e. Instead of screwing the clamping-bar fto the surface of e, I may employ, as shown in Fig. 3, links Z, securedby pivots at the ends tothe bars f and e, respectively. In this casethe. sheet of zinc will be clamped between the bars f and e, and thedepressions for receiving the wire or rod b' and the surrounding zincwill be at the lower outer edge of said bars.

In Figs. 4 and 5 I have shown a clampingbar, f, hollowed out upon itsunder side and covering the harm, and the sheet of zinc passes betweenthe bars f and m, the clamping-bar f being provided with lugs upon itsends, from which pivot-pins project to connect it to the links Z. Thebar m is free to move upon the ICD' surface of the bar e, and has aguide-pin, a, working in aslot in the surface of the bar c. The links Zare slotted to allow the bars f and m to remain in contact when the barsare drawn back and the links Z are swung, at which time the bar f can beraised and a space will be opened between the bars fand m to allow ofthe zinc plate being inserted in this space and beingadj usted beforethe plate is stretched. The action of the links Z in Fig. 3 as the rodsg and bars c are pushed out by the screw-rods is to compel theclampingbar f to press tightly against the zinc and force it against theinclined surface of bar c, and in Figs. 4 and 5 the action or" the linksZ as the rods g and bars c are moved is to press the barsf and m tightlytogether and hold and clamp the zinc plate between their surfaces. Thebars f and m have a slight movementtogether upon the surface of e aspressure is applied, and the pressure in both cases increases with thestrain.

rlhe angle at which the end portions of the sheet are bent may Varyaccording to the in; clination ofthe surfaces of the clamps.

I claim as my inventionl. In azincographic press, the combination, withthe bed a, of the bar (Z, for securing one edge of the sheet, the barse, and clampingbars f,for grasping the other edge of the sheet, and theguide-rods g, screw-rods It, collars Z, and plate 7s, for stretching themetallic sheet, substantially as set forth.

2. The bed a, in combination with the bars e, clamping-bars j', Wire orrod b', guide-rods g, and means, substantially as described, forstretching the zinc plate, as set forth.

3. .The combination, with the bed a, guiderods g, and bars c, ofclainping-barsf, links Z, Wire b', and mechanism, substantially asdescribed, for stretching the zinc plate, as set forth.

Signed by me this 23:1 day of February, A. D. 1884.

JOHN BROOKS.

Witnesses: y

GEO. T. PINCKNEY, HAROLD SERRELL.

